The present invention relates to an audiovisual system and, more particularly, to an audiovisual information presentation system for presenting various reference data images to an audience.
Audiovisual presentation using an optical image projector as the medium by which to enlarge and project reference material onto a projection screen is recently, in the interest of facilitating better understanding, a common occurrence wherever information is to be exchanged. When reference images are projected on the screen, the speaker's intent can be more readily grasped by the audience.
In particular, when a scholar or engineer presents the results of his or her study at a scientific or academic conference, it is critical for effective presentation of the study to supplement the speech with projected images. Since projection timing can be freely adjusted by the speaker, the flow of the presentation is not interrupted and the audience need not refer to their reference documents; instead, they can concentrate on the presentation without distraction.
Presentation apparatuses such as overhead projectors (OHP) or slide film projectors are the most commonly used optical image projection systems. An optical image projection system of this type, unlike a normal cineprojector, can clearly present images in a relatively bright room. When an overhead projector is used, images of materials to be projected are prepared in advance. These materials might include characteristic graphs, drawings associated with the results of a study, and so on. The graphs and drawings are drawn on special-purpose transparent sheets (known as OHP sheets). The OHP sheets are placed as desired on the document table of the projector by the speaker himself or by an assistant, and are optically projected onto a screen. If desired, a plurality of OHP sheets can be stacked on the table to project an overlapping image onto the screen.
After an OHP sheet has been projected, it is manually replaced with the next sheet. In general, used OHP sheets are stacked carelessly on, for example, a side table. Therefore, when a used OHP sheet is required for a subsequent projection, it may take a considerable amount of time to locate it from among the stack of already projected sheets, interrupting the flow of the presentation.
It has been still admitted among skilled persons that the image quality (particularly in resolution) of current CRT display units is not yet as good as that of conventional optical image projection system, CRT screens being, in addition, of a limited size. It is expected, then, that optical projection systems, capable of projecting a large, high-quality image, will continue to be the leading means of audiovisual presentation in the future. To provide a projector that can overcome the above-mentioned drawbacks of conventional projectors is, therefore, greatly desired.